Just to clarify, the natural is just a cautionary accidental in this case, right? The performer would play the upper note diatonically anyway if nothing was notated, correct? Coming from an E in the previous measure, an E# would be somewhat less common I suppose (and D#-Eb obviously not possible), unless previously encountered by the performer, or if all previous instances were whole steps.

I of course have no idea what comes prior, but is it possible to remove the natural here? Or is it necessary for clarity?

Diatonically - yes, but (I guess) only in the case you have established tonality. In the contemporary music lack of tonal-major/minor frames makes more freedom for interpretation. Here, the whole section plays around different intervalls, therefore I added the natural for clarification.